The objectives of this project are to develop, adapt, expand, and evaluate methodological procedures useful in epidemiologic studies of cancer. Methods of design and analysis of cohort studies were given particular emphasis this year, attention focusing on procedures for analysis of standardized mortality ratios, including regression methods and tests of equality and trend. Also considered were the adaptation and evaluation of multivariate epidemiologic models for analysis of case-control data. Other work focused on evaluating surrogate responses and assessing quality in case-control interview studies. Investigation of general epidemiologic techniques for studying environmental cancer continued, including the review of methods to evaluate the magnitude of low-dose radiation risks.